Unloader valve



Malh 26, 1946, l N. ASHTON E-r Al. 2,397,117.

` UNLOADER VALVE Filed Jan. 20, 1943 A IJ .AT ToRNcjrl Patented Mar. 26, 1946 UNITED STATE S PATENT OFFICE.v

UNLOADER VALVE Benjamin N. Ashton, Kingston, and Nelson G. Kling, Great Neck, N. Y.; assignors to Electrol Incorporated, Kingston, N. Y., a corporation of Delaware This invention relates to a pressure regulating valve for a high pressure hydraulic system, and

more particularly to an unloading valve for maintaining in the system a working pressurevd supplied from a constant pressure supply,

In the operation of hydraulic systems especially for aircraft use, the major consideration is weight and efficient operation of the units to preclude leakage due to the high pressures used. Another consideration is to insure the loading of the system with a uid medium to a predetermined pressure under all temperature conditions, and after loading the assurance that the pressure will be maintained regardless of the variation in temperature from a subnormal to an extremely high condition.

It is, therefore, an object of the present invention to provide a regulating valve in the pressure supply line of a hydraulic system, which permits the loading of fluid to a maximum working pressure and the holding of that pressure while the system is in a static condition, and

after the operation of the system the reloading of the system with uid to maintain the range of working pressure. v

A further object of the present invention is to provide a balanced poppet valve controlyto insure the by-passing of a fluid pressure supply when the pressure in the system supply port reaches a predetermined maximum value, and the same poppet valve to control the reloading of the uid pressure to the system port when the pressure therein reaches a predetermined minimum value.V

A further object is to provide a regulating valve of the poppet type in the pressure supply line of a hydraulic system which permits the loading of fluid under low temperatures, and the holding of that predetermined pressure at a low temperature.

A still further object is to provide a regulating valve of the poppet type in the pressure supply line of a hydraulic system which maintains that predetermined pressure and prevents any leakage under extremely high temperatures..

A still further object of the present invention is to provide a regulating valve mechanism which is compact, light in weight, simple in construction, ecient in use, and inexpensive to manufacture.

Other objects and characteristic features of the invention will appear from the following detailed description of one embodiment thereof, taken in connection with the accompanying drawing wherein identical reference numerals are applied to the same parts in the several figures, and in which Fig. 1 is a cross sectional view of the unloader 4 valve, illustrating all the structural and operating elements,

,Fig 2 is a top plan view of Fig. 1,.

Fig.-3 is a side elevational view of Fig. 1,

Fig. 4 is a view taken on line 4-4 of Fig. 1, and

Fig, 5 is an enlarged detail view of the double acting system ball poppet valve and both valve seats.'

In the preferred embodiment illustrated in Fig.v1, there is provided a casting I0 which is provided with three large borings II, I2 and I3 and two small interconnecting bores I4 and I5. There are also provided three ports, a pressure supply port I6, a. return port I1 and a system port I8. Mounted in the bore II of the casting Il! is the system poppet valve assembly I9, mounted in ,the bore I2 of the casting I0 is the system pressure check valve assembly 20, and mounted in the bore I3 of the casting I0 is the supply pressure by-passing or control valve assembly 2I The system poppet valve assembly I9 is comprised of a washer 23, a ball valve seat 24, a spacer 25, a ball 26, a ball seat 21, a spring actuated push rod 28 with a' spring 29, a seal 30, a retaining shell 3| with perforations 32, a seal 33, a seal lock 34, a cap nut 35 with a U cup seal 36, and alock nut 31 with seal 38; also, a spring retainer 39.

The cap nut 35 is formed with a centerbore 40 to permit the push rod 28 to move up or down in, and in addition has a screw cut head 4I and threaded external periphery to allow adjustments. The cap nut 35 also has an internal shoulder 42 which acts as a stop for the spring retainer 39. It is apparent that the compression of spring 29 may be varied by the adjustment of the cap nut 35, and, therefore, the resistance of the push rod 28 to an upward movement of the ball 26 may be predetermined. The retainer 'shell 3| is threadably secured in the bore II so that the perorations 32 will align with the connecting bore I5, and at the same time bear on the seal 30 to retain theA seats 21 and 24 in their proper relationship. The seal lock 34 and lock nut 3l are threadably secured to givea tight sealing action on the seals 33 and 38. The U cup 36 permits movements of the push rod 28 without leakage.

The check valve assembly 20 is comprised of a washer 45, a ball valve seat 46, a ball 41, a spring 48, a ball stop 49,2. retainer plug 50, a seal 5I,

with the interconnecting Vbore I4.`

and a sea1-.10ck.5z.-'1`.l1f. retain?? P1118 5 is threaiiably .secured in `the .bore I2 ,andf bears yagainst the ball seat 46 to retain it in position. The retainerV shell has apluralitylofperforations 54 to permit the ball check valve to be connected 5 p The han check 41 is normally retained in a seated position by the spring 48 as illustrated ,in Fig. 1, but in operation the iiuidyV supply from the'port I6 will force the ball!" oil the seat 46, passing on to the system port I8. The bal141 -will be moved on its seat enough to pass thel uid freely to the system port, but is prevented from moving more than desired bythe stop 48.

'Ihe control valve assembly 2 I is comprised of a piston cylinder and ball seat member 56. a piston 51, a ball 58, a spring 69, a retainer plug 60, a seal 6I, and a seallock 62. The piston 51V has a U cup 63 toiinsure the sealing of the pressure fluid at all times. The ball `seat member 56 is retained in the bore I3 by the threadably secured retainer plug 60. The piston 51 is slidably mounted in the cylinder seat 56 and serves but one function; that is. to use the back pressure from the system to move the piston andI unseat the poppet ball from its seat, this being performed by the contact of the piston head against the ball 58. 'Ihe spring 59 is seated in the retainer plug 6I) and bears against the poppet ball 58 to retain it on the seat 56.

Referring to Fig. 4, the piston 51 has a-perforatedhead 65 to permit the iiuid to be freely by-passed, and a projecting point 66 which normally contacts the ball 58.

Referring to Fig. 5, the bali 26 is movably po-i 35 sitioned between two ball seats 21 and 24 with a 4 very small degree of movement. The lower seat 24 controls the ilow of pressure-duid and the upper seat 21 controls the flow of exhaust uid to a return. The lower seat or pressure supply side is slightly smaller than the upper seat or exhaust side; therefore. when the pressure is great enough to overcome the force of the spring bearing on this ball 26 it 'will lift the ball from the one seat 24 and seat it against the upper seat 21. The ball will be maintained on the upper seat by the pressure diierential between the pressure side of the seat 21 and the return or negativeV pressure side. The action of the ball may be followed by reference to the Fig. 5 in which fluid pressure is PSI, spring pressure is P and the area of the seat will be A; thus, the formula of operation will be Assuming that the lower seat A=1 and in the upper seat A=2, also that a two pound spring is used for P, it is apparent that slightly more than 2 PSI would be requiredA to lift the poppet from the lower seat. After the ball has been lifted from the lower'seat the 2 PSI Will have twice the eective area to hold the ball against the upper seat. As the system pressure drops the pressure of the two-pound spring resets the poppet on the lower seat, when the pressure becomes 1 PSI.

As the system pressure is loaded to a maximum of slightly more than 2 PSI the poppet will be lifted from the lowes seat 24 and the pressure fluid passes on to the plunger 51 and moves it to the right, Vthus .opening the poppet valve 58 and allowing the supply pressure iluid to be bypassed to a return port I1.

. In addition to the resetting of ban poppet 2s, 76

assmiv when the system pressure drops-therefis thefreseatingof the poppet ball 68 bythe spring, vwhich atthefsametime forces Vthe pistonikto the left andthe exhausting of the uid that lies `behind this piston. Since the .poppet ',ball 26 is at that timeseated onthe lower seat, the exhaust uid -wil-l pass through the upper vseat 21 and on through the perforations 82 and ,outthe bore I5 to the return port I 1.

T hedesign of. this valve structure is dependent upon the systempressure, and the control of the particular lpressures for loading and unloading are dependent upon refinements in the novel design'of this structure.

Assuming that the maximum system pressure is set for 1,000 lbs. and a differential of lbs. is desired so that the valve will have a minimum or loading value of 880 lbs., and assuming that the valveshall permit adjustment so that the minimum pressure may be dropped or the maximum pressure may be increased, this adjustment will necessarily vary the diierenti'al pressures for loading and unloading, but the advantages of this particular design are such that the desired differential pressure is set at a predetermined low pressure, and increases slightly as the settings are stepped up to a maximum loading point. In the above instance, if the maximum pressure setting is adjusted from 1,000 lbs. to 1,200 lbs., the differential pressure will change from 120 lbs. to lbs.

With a known system pressure in the port I8, the area. of the ball valve seat 24 may be determined; thus a knownpressure on the ball may be established. To counteract this force a desired spring force is designed for the spring 29 with the retainer 35 set at a given point. This design is to assure the ball 26 being lifted from the seat 24 against the retaining force of the spring 29, by the maximum system back pressure. To assure the desired differential in loading and unloading pressure, after the maximumv or unloading pressure is established and the Vlower seat 24 is determined, the upper seat may be designed to give the desired differential; for instance, in

this case, with a setting ,of 1,000 lbs. and a, dierential of 120 lbs., the upper seat 21 will be Tlf larger in area than the lower seat 24. Referring to Fig. 1, another reiinement in the design may v be explained. Whenever any back pressure is created through the bore i5, such as the surge of supply pressure from the port I6 when the supply is by-passed to the return port i1, it will in turn act on the rod 28. At the particular stage where this occurs, the ball poppet 26 is held on the upper seat 21 against the force of the spring 29. Therefore, ythe back pressure through the bore I5 will tend to act upon the ball 26 to assistl the spring to lift the ball 26 from the seat 21. This condition is overcome by designing the rod 28 to be the same cross sectional area as the area of the seat 21, and by inserting the U-cup seal about the upperend of the rod 28. The back pressure force is thus equalized in two directions; the force upward on the rod 28 will be subtracted from the downward force of the spring 29, while the same degree of force will be added to that` The pressure iiuid will lift the ball 41 and supply the system through the port I8. When the system pressure reaches a maximum value, the back pressure will pass through the bore I4 to lift the ball 26 against the force of the spring 29.. Asl

already explained, the ball 26 will be transferred from the seat 24 to the seat 21 and held there by this maximum pressure. With the ball 26 seated on the upper seat 21, the back pressure from the system will pass through the bore I4, the seat 24, around the exterior of seat 21 through a port all to the U-cup face of the piston 51, forcing it to the right against the ball 58, which is retained by a spring 59. When the ball 58 is lifted from its seat, the supply pressure from the port I6 will be by-passed directly to a. return port I1, thereby reducing the pressure acting on ball 41, and, therefore, the greater back pressure in the system will seat the ball 41, acting as a check valve to retain the system pressure. In this manner the system reaches a maximum operating pressure and may be held at that pressure while in a static condition. When the system through operation drops to a predetermined minimum pressure, the valve must reset to permit reloading the system to its maximum'value. This occurs as follows: The dropping of pressure in the system reduces the PSI on the ball 28 and the holding pressure on the ball 41. The spring 29 will return the ball 26 to the lower seat 24. When the ball 26 is seated on the lower seat the ypressure iluid holding the piston 51 will be exhausted through the upper seat 21 and on to the return port I1; in addition to the exhausting of this fluid, the b' li 58 will be returned to its seat by the spring 8, and the supply pressure will lift the ball 41 from its seat, thus supplying iluid to the system to boost the operating pressure. Thus a complete cycle of operation occurs. Also in operation it is desirable to adjust the valve to maintain a particular range of pressure which in this instance may be set as low as 650 lbs., or it may be set as high as 1,450 lbs., but the differential of pressures will remain between 120 lbs. and approximately 200 lbs., depending on the setting. This adjustment for a given valve with a predetermined spring value is dependent upon the position of the cap nut 35.' When screwed all the way down, a maximum pressure may be attained; when unscrewed to its highest point, a minimum pressure may be attained.

The embodiment of the invention herein disclosed is merely illustrative and may be modined and departed from in many ways without departing from the spirit and scope of the invention, as pointed out in and limited solely by the appended claims.

What is claimed is:

1. A fluid control valve comprising a valve casing having a bore therein, a first annular valve seat member in one end of said bore having a centrally located port therein, a second annular valve seat member in said bore having a centrally located port of larger diameter than the port in said rst valve seat member, a ball between said valve seat members and engageable therewith alternately to close the ports therein, annular spacer means interposed between said valve seat members having an opening for receiving said ball loosely and a port extending outwardly therethrough from said opening, means in said bore for retaining said valve seat and spacer members in fixed relationship to said casing, spring means normally urging said ball against said first valve seat member, and separate passages in said' casing communicating with each of said ports.

2. A fluid control valve comprising a valve casing having a bore therein, a first annular valve seat member in one end of said bore having a centrally located port therein, a second annular valve seat member in said bore having a centrally located port of larger diameter than the port in said rst valve seat member, a ball between said valve seat members and engageable therewith alternately to close the ports therein, annular.

spacer means interposed between said valve seat members having an opening for receiving said ball loosely and a port extending outwardly therethrough from said opening, means in said bore for retaining said valve seat and spacerv members in fixed relationship to said casing, a plunger extending axially of the bore and engaging said ball, means urging said plunger against said ball, to seat the latter against the first-mentioned valve seat member, sealing means interposed between said plunger and said casing for preventing escape of fluid from said casing around said plunger, and separate passages in said casing communicating with each of said ports.

3. A fluid control valve comprising a casing having a bore therein, a pair of spaced apart valve seat members therein having ports of diiferent areas, a valve member interposed between said seat members and movable to engage said seat members selectively to close the ports therein, a plunger extending axially of said bore having a body portion with cross-sectional area equal to the area of the larger port, and a reduced end portion projecting through said larger port into engagement with said valve member, one end of said body portion being exposed externally of said casing, sealing means between said one end and said casing receiving said one end slidably, a spring engaging said plunger to urge said valve member into engagement with the valve seat member having the smaller port, and three separate passages in said casing communicating with said bore between and on opposite sides of said valve seat members.

BENJAMIN N. ASHTON. NEIBON G. KLING. 

